ABSTRACT

BackgroundAntihistamines are the standard treatment for chronic idiopathic urticaria (CIU). For patients whose urticaria is unresponsive to antihistamines, the treatment options are limited. During the previous decade, there have been several case reports demonstrating success with sulfasalazine therapy. In this article, we present a case series evaluating sulfasalazine therapy for antihistamine-unresponsive CIU.

ObservationsNineteen patients with antihistamine-unresponsive CIU were treated with sulfasalazine between 2002 and 2005. During sulfasalazine therapy, 14 patients (74%) reported significant improvement, 4 patients (21%) reported minimal improvement but were not satisfied with their symptom relief, and 1 patient (5%) reported a worsening of symptoms. Of the 13 patients who required systemic steroids to control their urticaria, all were able to reduce or discontinue steroid use during sulfasalazine therapy. Although 7 patients (37%) had adverse effects (eg, nausea, headache, mild or transient leukopenia, and transaminitis) that were thought to be caused by the use of sulfasalazine, they all kept taking the drug.

ConclusionsThis case series demonstrates that sulfasalazine can be a successful and safe treatment option for patients with CIU who have not responded adequately to treatment with antihistamines. Sulfasalazine was steroid sparing in all subjects who were steroid dependent.

Chronic idiopathic urticaria (CIU) is defined as the occurrence of close-to-daily wheals and pruritus for a duration of at least 6 weeks, without an obvious cause. The wheals usually resolve in less than 24 hours. It has been estimated that 15% to 23% of the US population will experience acute or chronic urticaria at some point in their lifetime, and there is an approximately 0.5% lifetime prevalence of CIU in the general population.1- 3 Chronic idiopathic urticaria more commonly affects women than men (2:1), is more commonly seen in the adult population,4 and is associated with angioedema in 50% to 90% of cases.5,6 The discomfort and negative cosmetic impact experienced with chronic urticaria, as well as the elusive pathogenesis and the lack of satisfactory control of symptoms with standard therapies, can be very frustrating for patients and health care providers. It has also been estimated that the disability suffered by those with CIU is equal to that observed with triple-vessel coronary artery disease.7

Great efforts have been made to identify the pathogenesis of this disease, with the 2 most commonly proposed theories being an infectious or autoimmune origin. Infectious agents have long been thought to play a role in the development of CIU, but definitive proof is still lacking. For example, Helicobacter pylori has been extensively studied as a possible causative agent, specifically in reference to its ability to cause formation of autoantibodies through the immunogenicity of its cell envelope.8 Currently, there is conflicting evidence in the literature as to an association between the eradication of H pylori and improvement of urticaria.9- 12 Fungi, such as Candida albicans and Malessezia furfur, have also been implicated.13,14

More recently, there have been studies that have found that approximately 30% to 60% of patients with CIU have an autoimmune component.15- 17 Anti-IgE antibodies and functional antibodies against the α chain of the high-affinity IgE receptor found on mast cells, basophils, and antigen-presenting cells have been isolated from the serum of patients with CIU.18- 20 The role that autoimmunity plays in CIU is also supported by the association of CIU with autoimmune thyroid disease. Abnormal thyroid function has been found in 12% to 19% of patients with CIU,21- 23 with 2 studies demonstrating that 14% to 27% of patients with CIU have thyroid autoantibodies compared with 6% of the general population.23,24

Currently, antihistamines, which generally work by alleviating the symptoms rather than enacting a cure, are the standard treatment for CIU.25,26 With the recent advent of nonsedating or minimally sedating H1 receptor antagonists, some patients with CIU have found relief from symptoms without the adverse effect of excessive drowsiness. Unfortunately, there are those whose urticaria does not respond to treatment with antihistamines, with some studies reporting a 5% to 12% failure rate with fexofenadine hydrochloride therapy.27,28 For those individuals, H2 receptor antagonists, leukotriene antagonists, and systemic corticosteroids have also been used, with varying degrees of success.29,30 The potential role of an autoimmune mechanism in at least some cases of CIU has led to the use of alternative therapies focusing on immunomodulation. For example, recent randomized trials have demonstrated the efficacy of cyclosporine.31,32 There have also been smaller, uncontrolled studies indicating a potential benefit from dapsone33 and hydroxychloroquine,34 and additional case reports have shown promise with other medications such as methotrexate35,36 and cyclophosphamide.37 Despite these advances, many persons still suffer from therapy-resistant CIU. There is a need for further investigation of immunoregulatory agents with more benign adverse effect profiles that can effectively reduce or eradicate the symptoms of urticaria and decrease the need for systemic steroids.

Over the last decade, there have been sporadic case reports demonstrating successful alleviation of symptoms with the use of sulfasalazine.38- 40 We present a review of the literature and a retrospective review of our own institutional experience with sulfasalazine for the treatment of recalcitrant CIU. In 2 patients taking sulfasalazine, we also noted a functional change in the histamine-releasing capabilities of their basophils before and after sulfasalazine treatment, a finding that coincided with clinical improvement (data not shown).

METHODS

RETROSPECTIVE CHART REVIEW

We performed a retrospective medical chart review of 19 patients diagnosed with CIU and subsequently treated with sulfasalazine at Johns Hopkins Bayview Medical Center, Baltimore, Md, from 2002 to 2005. The study was approved by the institutional review board at the Johns Hopkins Medical Institutions, Baltimore. The diagnosis of CIU was based on clinical history and physical examination and was supported by skin biopsy findings in 17 cases (89%). The remaining 2 patients did not have any biopsy data on record and were diagnosed as having CIU solely on their disease presentation. The following information was obtained: disease duration, history of angioedema, presence of thyroid autoantibodies (antimicrosomal and antithyroglobin), thyroid function, dosage of sulfasalazine therapy, subjective clinical response to sulfasalazine therapy, adverse effects during sulfasalazine therapy, therapies for CIU used before and after sulfasalazine therapy, and skin biopsy findings. Before the initiation of sulfasalazine therapy, baseline blood work, including kidney and liver function tests, a complete blood cell count, and determination of thyrotropin and antimicrosomal and antithyroglobin antibodies, was performed. A punch biopsy of an urticarial wheal was performed to rule out other diagnoses such as urticarial vasculitis and to further characterize the urticaria as lymphocyte or neutrophil predominant. Patients were counseled on the potential adverse effects of sulfasalazine, including headache, photosensitivity, gastrointestinal distress, liver and kidney abnormalities, leukopenia, and reversible oligospermia. The sulfasalazine therapy was started at a dosage of 500 mg/d and increased by 500 mg each week until a satisfactory clinical response was achieved or until a daily dose of 2 to 4 g/d was reached. During dose escalation, blood work was repeated weekly and then every 3 months after the final dosage had been reached.

Based on subjective reports, the patients were categorized into the following groups: significant or nonsignificant improvement, no change, or worse with the use of sulfasalazine. Patients with significant improvement had at least a 50% reduction of their urticaria according to a subjective report of response using either a symptom severity scale from 1 to 10 or a report of symptom frequency. One of patients with significant improvement was classified as such based on the statement in his medical record that during sulfasalazine therapy his urticaria was “minimally symptomatic.” Nonsignificant improvement included those who noted a minimal decrease in urticaria but were not satisfied enough to continue taking sulfasalazine. Anyone not classified as having significant improvement was considered a treatment failure. Patients generally had a clinical response to sulfasalazine within 2 to 4 weeks but required a full 8-week course before being classified as a treatment failure.

REVIEW OF THE LITERATURE

A computer search of the MEDLINE database (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi) was performed, as was a review of the reference section of each primary source. All cases of chronic urticaria that were treated with sulfasalazine and described in the English-language medical literature between the years of 1966 and 2005 were identified.

RESULTS

Nineteen patients from the Johns Hopkins Bayview Medical Center were diagnosed as having CIU and started sulfasalazine therapy between the years of 2002 and 2005. Fifteen patients (79%) were female, and the mean ± SD age was 39 ± 3 years. The mean ± SD duration of CIU symptoms before the initiation of sulfasalazine therapy was 81 ± 25 months, with a median of 60 months. The dosage ranged from 0.5 to 4 g/d, with a mean ± SD dose of 2 ± 0.16 g/d. Fourteen patients (74%) had a history of angioedema, and of the 16 patients with thyroid studies, 6 (38%) had evidence of thyroid autoimmunity (Table 1). All 19 patients had tried at least 2 different antihistamines (including sedating and nonsedating). According to the patients' reports, they had taken as much antihistamine as they could tolerate (in terms of adverse effects) and still did not have adequate control of their CIU symptoms.

Fourteen patients (74%) reported significant improvement with the use of sulfasalazine. Four patients (21%) reported nonsignificant improvement, and 1 patient (5%) felt that the urticaria worsened during sulfasalazine therapy (Table 2). The average maximum dosage of sulfasalazine therapy was 1.8 g/d for those with significant improvement and 2.6 g/d for those who failed treatment. Treatment failure was not associated with sex, ethnicity, duration of CIU symptoms, characteristics of the cellular infiltrate in the biopsy specimen, history of angioedema, thyrotropin level, presence of antimicrosomal or antithyroglobin antibodies, or previous steroid use.

Thirteen patients required intermittent or long-term daily treatment with systemic steroids before initiation of sulfasalazine therapy for control of their urticaria. Of those patients, 9 did not require any steroid use during treatment with sulfasalazine, and the other 4 were able to reduce their dose of steroids 3- to 4-fold. One patient classified as a treatment failure did require steroids during sulfasalazine therapy, whereas she had not required any previously.

Six patients have been able to completely stop taking all other urticaria medication, including antihistamines and systemic steroids. Two of the aforementioned patients have tapered off sulfasalazine, and another has reduced her dosage of sulfasalazine by 50%, all without a recurrence of urticarial symptoms. Sulfasalzine therapy was tapered in the 3 others, and they developed increased urticaria, requiring a reinitiation of or an increase in the dosage.

Adverse effects attributed to sulfasalazine use were reported by 7 patients (37%). They ranged from mild headache and gastrointestinal discomfort to mild leukopenia (white blood cell count, 3.7×103/μL and 4.2×103/μL) in 2 patients and elevated liver enzyme levels (aspartate aminotransferase/alanine aminotransferase, 54/75 IU/L) in 1 patient. All of these patients were able to continue the use of sulfasalazine, and the cases of leukopenia and elevated liver enzyme levels resolved spontaneously or with dose reduction.

There have been a few small case reports in the literature citing successful treatment of CIU with sulfasalazine in 6 subjects (5 men and 1 woman; mean age, 39.6 years). Three subjects were diagnosed as having CIU and 3 as having pressure-induced urticaria.38- 40 All 6 subjects had been diagnosed as having urticaria that was refractory to standard antihistamine treatment, and all required treatment with systemic steroids for control. Complete resolution of the urticaria was seen in all patients after they took the sulfasalazine for anywhere from a few days to multiple weeks. The dosage of sulfasalazine therapy required for response ranged from 2 to 4 g/d, with a mean of 3.2 g/d. All subjects were able to stop using corticosteroids but did require a maintenance dose of sulfasalazine (2-3 g/d). The urticaria flared in 3 patients who attempted dose reduction below their maintenance dose. The mean follow-up period was 9 months. No adverse effects were reported, and 50% of the patients were reported to have undergone routine blood work during the treatment. Two patients also received folate supplementation (1 mg/d) during treatment. In summary, these patients were reported to have complete clearance of their urticaria, were able to stop taking systemic steroids, and had no reported adverse effects.

COMMENT

Sulfasalazine is composed of a sulfapyridine covalently linked to 5-aminosalicylic acid. The sulfa moiety is known to have antimicrobial properties, whereas the salicylate component acts as an anti-inflammatory agent. Despite our knowledge of the structure and activity of sulfasalazine, we have a poor understanding of how it produces therapeutic effects in disease. It has been used most extensively in the treatment of inflammatory bowel disease (ie, Crohn disease and ulcerative colitis), and it also been used to treat rheumatoid arthritis, psoriasis, ankylosing spondylitis, and other spondyloarthropathies.41- 46

We are reporting our use of sulfasalazine over the previous 3 years to treat 19 patients with CIU that was not adequately controlled with standard therapy. We classified 14 patients (74%) as having significant improvement with sulfasalazine therapy, and 6 of the patients were able to stop taking all other medication for CIU. Five patients (26%) were not satisfied with sulfasalazine and were considered treatment failures despite the fact that 4 of them did experience minimal improvement in symptoms. We also found that all 13 patients who had previously required systemic steroids for CIU control were able to completely stop or reduce their steroid intake during sulfasalazine therapy.

It is also worth noting that the patients in our study had different demographics from those of previously described CIU populations. Our cohort had a greater female-male ratio (4:1 vs 2:1)4 and an increase in thyroid autoimmunity (38% vs 14%-27%).23,24 Although we were unable to perform quality-of-life measurements owing to the retrospective nature of this study, it is likely that our cohort represents a more severe form of the disease. All patients seen in clinic were referred for recalcitrant CIU, as their urticaria had been inadequately controlled by antihistamines and other standard therapies. Also, more than half of the patients (68%) had required systemic steroids, and the mean CIU duration before the initiation of sulfasalazine therapy was 81 months. It is possible that being female and having evidence of thyroid autoimmunity may be associated with a more severe form of CIU, as both females and thyroid autoimmunity were overrepresented in our cohort.

Our follow-up period ranged from a few months to 3 years, and because of that we have extremely variable longitudinal data on our patients. We do know that 6 patients with significant improvement were able to taper their sulfasalazine dosage. Two of the 6 patients were able to stop taking all other urticaria medications and then successfully tapered off sulfasalazine therapy and have been urticaria free for anywhere from 3 to 13 months. Another 2 were able to taper off sulfasalazine and all other urticaria medication for 4 to 12 months but then developed a recurrence. The last 2 patients tapered their dosage of sulfasalazine therapy from 2 g/d to 1 g/d, and 1 developed a mild increase in urticaria.

The dosage of sulfasalazine therapy for various inflammatory conditions has ranged widely from 2 to 6 g/d. We initially set our maximum dose at 4 g/d, but after we treated a number of patients, it became apparent that those without improvement at 2 g/d rarely improved at higher doses. Also, adverse effects have been reported to occur with greater frequency at higher doses, so we rarely prescribe a dose higher than 2 g/d. Of the patients who responded, most started to see an improvement after a few weeks, although some required closer to 1 month for any appreciable change in symptoms.

Seven patients (37%) reported adverse effects from the use of sulfasalazine, including gastrointestinal discomfort, nausea, and mild headache, as well as leukopenia and elevated liver enzyme levels. These complications have been reported previously, and all of the patients were able to continue taking sulfasalazine, although some reduced their dose from 2 g/d to 1.5 g/d. Also, the abnormal liver enzyme levels and leukopenia had resolved on follow-up testing. Because of the adverse effect profile of sulfasalazine and the laboratory monitoring required, we do not suggest it as a first-line agent for CIU. Instead, we believe that sulfasalazine therapy is most beneficial when antihistamines and other common medications with a more benign adverse effect profile (eg, H2-receptor antagonists and leukotriene antagonists) do not adequately control symptoms. Based on the current risk-benefit profile, it is reasonable to try sulfasalazine therapy instead of treatment with medications such as systemic steroids or cyclosporine. Because of concerns about prescribing sulfasalazine for patients reported to be sulfa allergic, 1 patient (not included in our data set) was started on olsalazine therapy (maximum dose, 1.5 g/d). Of note, she also experienced significant improvement in her urticaria.

We are aware that the retrospective nature of our case series does introduce certain biases, as we are relying on the patient record as the sole source of information. We were not able to have any objective measurement of change in disease during sulfasalazine therapy, and we were not able to standardize follow-up for all patients. Despite these problems, we do believe that the steroid-sparing effects and the impressive reduction in urticaria that the majority of our patients with fairly severe and long-standing, recalcitrant CIU experienced indicate that sulfasalazine threapy should be considered for patients with CIU that does not respond adequately to antihistamines.

It is not clear how sulfasalazine is able to reduce and even resolve CIU, but looking at the proposed causes of CIU may help to elucidate the mechanism of action exerted by sulfasalazine. Overall, there has not been enough evidence to firmly establish a causal relationship between any infectious agent and CIU,47 but if there were such a relationship, sulfasalazine might be able to reduce the urticaria, at least in part, through its antimicrobial properties. Interestingly, sulfasalazine has also been effective in the treatment of other autoimmune diseases such as rheumatoid arthritis and inflammatory bowel disease. While we do not know whether our patients have an autoimmune basis for their urticaria, it is possible that sulfasalazine therapy is combating the autoimmune processes that lead to CIU.

In addition to a potential autoimmune component and/or infectious pathogenesis, basophils and mast cells are thought to play a role in CIU. A recent publication reports a difference in the FcεRI-signaling molecules in basophils and mast cells of patients with CIU that may be critical for development of urticaria.48 In the 1990s, Lee and Kim49 demonstrated reduced histamine release in the peritoneal mast cells of rats, when treated with sulfasalazine. Similar studies on human mast cells and basophils found the opposite, ie, that sulfasalazine enhanced IgE-induced histamine release.50,51 Interestingly, the metabolite of sulfasalazine, 5-aminosalicylic acid, caused a reduction of IgE-induced release of histamine in human basophils and mast cells.50 Although it is unclear how this alteration in basophil and mast cell function affects the presentation of CIU, we believe that it is possible that the clinical improvement seen with sulfasalazine therapy may be associated with a distinct phenotypic change in the histamine-releasing capabilities of basophils and/or mast cells.

Chronic idiopathic urticaria continues to be a frustrating disease for many patients. Therefore, we must look for new treatments and evaluate potential causes of this disease. In summary, we believe that the findings we report suggest that sulfasalazine therapy can be an effective and safe treatment for patients with recalcitrant CIU. Its ability to improve symptoms in the majority of our patients and to greatly reduce systemic steroid use indicates that it should be considered when standard therapies fail. We also believe that our initial results warrant further studies to better elucidate the efficacy of sulfasalazine in the treatment of CIU and to help clarify the mechanism of action of sulfasalazine in patients with CIU.

Author Contributions: Dr Beck had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: McGirt and Beck. Acquisition of data: McGirt, Vasagar, Gober, Saini, and Beck. Analysis and interpretation of data: McGirt, Vasagar, Gober, Saini, and Beck. Drafting of the manuscript: McGirt, Saini, and Beck. Critical revision of the manuscript for important intellectual content: McGirt, Saini, and Beck. Statistical analysis: McGirt and Beck. Obtained funding: Saini and Beck. Administrative, technical, and material support: McGirt. Study supervision: Beck.

Funding/Support: This study was supported in part by grants AI50024 (Dr Beck) and AI01564 (Dr Saini) from the National Institutes of Health, Bethesda, Md.

Correspondence

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